He added: “Murray is a great, great talent – one of the biggest ever, and a big part of it is not being used because his mindset is not calm. He gets frustrated very easily. When he’s winning he has booming confidence but, once he starts losing, his mind turns around and he looks lost. He starts talking to his box, and this distracts his mind.”

He says Murray, who won his first match since becoming a father by beating Marcel Granollers 6-4, 7-6 in Indian Wells, would benefit from emulating his son, who is a week younger than the Scot and who has known him since they met in a junior tournament in France when they were 11, a match Murray won.

“When Federer and Nadal were the best two players in the world, they took much more out of Novak. For a couple of years Novak was giving his best and trying everything, changing his forehand, his serve, because he had a goal to beat Nadal and Federer. Now Murray has to do the same. He needs to put himself in the same position: to say, ‘OK, Novak, you are better at this and this. I need to make myself better in this and this in order to get there.’ They make each other better.”

Murray has lost 22 times in 31 matches against Djokovic – most recently in the final of the Australian Open – but he has won his two slams in finals against the Serb. He admitted before the tournament the world No 1 would have to have an off day or two not to win the title.

Djokovic Sr thinks his son “will be the best tennis player in history”. He adds: “I have been saying it since he entered tennis. Surely he will be one of the best sportsmen ever. All of it is because he was sent from God.

As a family, we tried to make God’s wish come true. He can win another 10 grand slams.”

Despite outward appearances of a cooling in what Murray describes as a “professional friendship” between him and Djokovic, the Serb’s father describes them as “amazing friends”, adding: “At the moment they cannot be good friends outside of tennis, because they are rivals. But, once they have finished their careers, they are going to be much better friends than they are today.”

He is, however, not so complimentary about Federer. “When Serbia played Switzerland in Geneva [in 2006], Novak was just 19 at the time. He had a deviation of his sinuses and couldn’t breathe. He had a problem with staying in long matches and long points. And Federer tried in every possible way to disrespect him because of his breathing problem. He showed himself to be the best player in the world but not as a good person at that time. Nobody has ever treated Novak like this. I don’t understand why Federer is still playing tennis. Why does he still play? He’s already 34.”